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B8W5 > THE THYROID IN HEALTH AND DISEASE > Flashcards

THE THYROID IN HEALTH AND DISEASE Flashcards

1
Q

outline the normal control of the thyroid?

A

Thyroid secretes T3 and T4 under stimulation from the pituitary gland secreting thyroid-stimulating hormone. The pituitary gland is stimulated by the release of thyrotropin-releasing hormone from the hypothalamus. T3 and T4 secretion inhibits the pituitary and hypothalamus= negative feedback

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2
Q

what does the thyroid secrete?

A

T3 T4 and calcitonin

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3
Q

whats the function of calcitonin?

A

controls levels of calcium and phosphorous in the blood
stimulates osteoblast activity
inhibits osteoclast activity
decreases renal calcium/phosphorous reabsorption

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4
Q

what are the functions of thyroid hormone?

A

increase metabolism
have positive inotropic and chronotropic effects on the heart
grows and development of the skeleton and CNS
heat production because of increased metabolism

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5
Q

how does thyroid hormone increase metabolism?

A

increasing number and size of mitochondria, increasing enzymes in the metabolic chain, increasing Na+/K+ ATPase activity.

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6
Q

what is a thyroid hormone deficiency linked to?

A

mental or growth retardation

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7
Q

describe how thyroid hormones are synthesised?

A

thyroglobulin is synthesized and secreted into the follicular lumen. iodine is taken into the follicular cells and can attach to tyrosine to form diiodo tyrosine or monoiodotyrosine. these iodinated tyrosine molecules link together to form thyroglobulin colloid which is combined with a lysosome and cleaved to form T3 and T4

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8
Q

what is T4?

A

thyroxine- has 4 iodides attached and is the inactive form

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9
Q

what is the function of thyroid stimulating hormone?

A

Stimulates the uptake of iodine and the synthesis of thyroid hormone, stimulates the uptake of the colloid, and reduces the growth of the thyroid gland

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10
Q

describe how thyroid hormones act on their target cells?

A

T3 and T4 bind to a target cell and are transported into the nucleus where they bind into the thyroid hormone receptor and the thyroid hormone response element of the DNA. As a result, gene transcription is altered so that synthesis of new proteins is regulated.

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11
Q

what are some causes of primary hypothyroidism?

A

athyreosis, ectopic thyroid, dyshormonogenesis, iodine deficiency

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12
Q

why is primary hypothyroidism most common in the Andes, Himalayas and Central Africa?

A

as they don’t have sufficient iodine in their diets

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13
Q

what are some causes of secondary hypothyroidism?

A

pituitary tumours, pituitary granulomas and ‘empty Sella’ syndrome

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14
Q

what are some causes of tertiary hypothyroidism?

A

hypothalamic disorders or isolated thyrotropin deficiency

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15
Q

what is congenital hypothyroidism?

A

a condition resulting from an absent or under-developed thyroid gland (dysgenesis) or one that has developed but cannot make thyroid hormone because of a ‘production line’ problem

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16
Q

what’s the usual treatment for congenital hypothyroidism?

A

life ling thyroxine

17
Q

what are some symptoms of primary hypothyroidism?

A 
fatigue
cold intolerance
depression
poor concentration
musculoskeletal aches and pains
carpel tunnel syndrome
constipation
hoarse voice
menorrhagia
dry clay skin
thinning hair
bradycardia
har loss
anaemia
puffy eyes
18
Q

what is Hashimoto’s disease?

A

autoimmune thyroiditis

19
Q

what is the pathophysiology of Hashimoto’s disease?

A

the formation of antithyroid antibodies that attack the thyroid tissue, causing progressive fibrosis

20
Q

what’s the treatment of hypothyroidism?

A

Administration of thyroxine and triiodothyronine for the long term.

21
Q

what are the most common causes of hyperthyroidism?

A

autoimmune thyroid diseases, grave’s disease, postpartum thyroiditis, toxic nodular goitre, and toxic adenoma

22
Q

what is a goitre?

A

the swelling in the neck resulting from an enlarged thyroid

23
Q

what are some causes of goitre?

A

hyperthyroidism
hypothyroidism
euthyroidism (creating a typical amount of thyroid hormones)

24
Q

Why does hypothyridism cause a goitre?

A

Sensing a low hormone level, your pituitary gland produces more TSH to stimulate the thyroid, which then causes the gland to enlarge.

25
Q

why does hyperthyroidism cause a goitre?

A

overstimulation of the thyroid

26
Q

what is Grave’s disease?

A

an autoimmune condition where your immune system mistakenly attacks your thyroid which causes it to become overactive.

27
Q

what are some symptoms and signs of hyperthyroidism?

A

weight loss, lack of energy, heat intolerance, anxiety, increased sweating, increased appetite, thirst, palpitations, looseness of bowels, goitre, tremor, warm skin, tachycardia, hyperkinesis, systolic hypertension, muscle weakness, ankle swelling, splenomegaly etc…

28
Q

what are the treatment options for hyperthyroidism?

A

hormone replacement with thioamides or beta blockers
thyroidectomy
radioactive iodine treatment

29
Q

what do we test for free T4 to find out?

A

to test for hypothyroidism and hyperthyroidism.

30
Q

what do we test for free T3 to find out?

A

to test for hyperthyroidism.

`

31
Q

why do we test for TSH levels?

A

to test for hypothyroidism, and hyperthyroidism, to screen for secondary hypothyroidism

32
Q

what can interfere with a treatment of thyroxine?

A

calcium and iron supplements

33
Q

what is the parathyroid hormone’s function?

A

activates osteoclasts with the aim to maintain calcium and phosphate levels, increases calcium absorption from the food, promotes activation of vitamin D, and increases calcium reabsorption from the kidneys.

34
Q

what are parathyroid hormones inhibited by?

A

hypercalcaemia and vitamin D

35
Q

what is the half-life of the parathyroid hormone? why?

A

3-4 minutes

its rapidly metabolised in the liver and kidney

36
Q

what is primary hyperparathyroidism?

A

where one or more of the parathyroid glands make too much parathyroid hormone- can lead to the loss of bone tissue

B8W5 (5 decks)

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